'\" t
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.\" $Id: ncurses.3x,v 1.229 2024/07/27 20:10:07 tom Exp $
.TH ncurses 3X 2024-07-27 "ncurses 6.5" "Library calls"
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.
.SH NAME
\fB\%ncurses\fP \-
character-cell terminal interface with optimized output
.SH SYNOPSIS
.nf
\fB#include <curses.h>
.fi
.SH DESCRIPTION
The \*(``new curses\*('' library offers the programmer a
terminal-independent means of reading keyboard and mouse input and
updating character-cell terminals with output optimized to minimize
screen updates.
.I \%ncurses
replaces the
.I curses
libraries from
System V Release 4 Unix (\*(``SVr4\*('')
and
4.4BSD Unix,
the development of which ceased in the 1990s.
This document describes
.I \%ncurses
version 6.5
(patch 20240831).
.PP
.I \%ncurses
permits control of the terminal screen's contents;
abstraction and subdivision thereof with
.I windows
and
.IR pads ;
acquisition of keyboard and mouse events;
selection of color and rendering attributes
(such as bold or underline);
the definition and use of
.I "soft label"
keys;
access to the
.I \%term\%info
terminal capability database;
a
.I termcap
compatibility interface;
and an abstraction of the system's API for manipulating the terminal
(such as \fI\%termios\fP(3)).
.PP
.I \%ncurses
implements the interface described by X/Open Curses Issue\ 7.
In many behavioral details not standardized by X/Open,
.I \%ncurses
emulates the
.I curses
library of SVr4 and provides numerous useful extensions.
.PP
.I \%ncurses
man pages employ several sections to clarify matters of usage and
interoperability with other
.I curses
implementations.
.bP
\*(``NOTES\*('' describes issues and caveats of which any user of the
.I \%ncurses
API should be aware,
such as limitations on the size of an underlying integral type or the
availability of a preprocessor macro exclusive of a function definition
(which prevents its address from being taken).
This section also describes implementation details
of significance to the programmer but which are not standardized.
.bP
\*(``EXTENSIONS\*('' presents
.I \%ncurses
innovations beyond the X/Open Curses standard and/or the SVr4
.I curses
implementation.
They are termed
.I extensions
to indicate that they cannot be implemented solely by using the library
API,
but require access to the library's internal state.
.bP
\*(``PORTABILITY\*('' discusses matters
(beyond the exercise of extensions)
that should be considered when writing to a
.I curses
standard,
or for multiple implementations.
.bP
\*(``HISTORY\*('' examines points of detail in
.I \%ncurses
and other
.I curses
implementations over the decades of their development,
particularly where precedent or inertia have frustrated better design
(and,
in a few cases,
where such inertia has been overcome).
.PP
A
.I curses
application must be linked with the library;
use the
.B \-lncurses
option to your compiler or linker.
A debugging version of the library may be available;
if so,
link with it using
.BR \-lncurses_g .
(Your system integrator may have installed these libraries such that you
can use the options
.B \-lcurses
and
.BR \-lcurses_g ,
respectively.)
The
.I \%ncurses_g
library logs events describing
.I \%ncurses
actions
to a file called
.I \%trace
in the current directory.
See section \*(``ALTERNATE CONFIGURATIONS\*('' below.
.SS "Application Structure"
A
.I curses
application uses information from the system locale;
\fI\%setlocale\fP(3) prepares it for
.I curses
library calls.
.PP
.RS 4
.EX
setlocale(LC_ALL, "");
.EE
.RE
.PP
If the locale is not thus initialized,
the library assumes that characters are printable as in ISO\ 8859-1,
to work with certain legacy programs.
You should initialize the locale;
do not expect consistent behavior from the library when the locale has
not been set up.
.PP
\fB\%initscr\fP(3X) or \fB\%newterm\fP(3X)
must be called to initialize
.I curses
before use of any functions that deal with windows and screens.
.PP
To get character-at-a-time input without echoing\(emmost interactive,
screen-oriented programs want this\(emuse the following sequence.
.PP
.RS 4
.EX
initscr(); cbreak(); noecho();
.EE
.RE
.PP
Most applications would perform further setup as follows.
.PP
.RS 4
.EX
noqiflush();
keypad(stdscr, TRUE);
.EE
.RE
.PP
A
.I curses
program then often enters an event loop of some sort.
Call \fB\%endwin\fP(3X) before exiting.
.SS Overview
A
.I curses
library abstracts the terminal with a
.I \%SCREEN
data structure,
and represents all or part of its display
with
.I \%WINDOW
structures.
Distinct properties apply to each;
for example,
the
.I "line discipline"
of a typical Unix terminal driver
is in one of three modes:
raw,
\%cbreak,
or normal (\*(``cooked\*('').
In
.IR curses ","
the line discipline is a property of the screen,
applying identically to all windows associated with it.
.PP
A
.I window
is a rectangular grid of character cells,
addressed by line and column coordinates
.RI ( y ,
.IR x ),
with the upper left corner as (0, 0).
A window called
.BR \%stdscr ,
the same size as the terminal screen,
is always available.
Create others with \fB\%newwin\fP(3X).
.PP
A
.I curses
library does not manage overlapping windows
(but see below).
You can either use
.B \%stdscr
to manage one screen-filling window,
or tile the screen into non-overlapping windows and not use
.B \%stdscr
at all.
Mixing the two approaches will result in unpredictable and undesired
effects.
.PP
Functions permit manipulation of a window and the
.I cursor
identifying the cell within it at which the next operation will occur.
Among those,
the most basic are \fB\%move\fP(3X) and \fB\%addch\fP(3X):
these place the cursor within and write a character to
.BR \%stdscr ,
respectively.
.PP
Frequent changes to the terminal screen can cause unpleasant flicker or
inefficient use of the communication channel to the device,
so as a rule the library does not update it automatically.
Therefore,
after using
.I curses
functions to accumulate a set of desired updates that make sense to
present together,
call \fB\%refresh\fP(3X) to tell the library to make the user's screen
look like \fBstdscr\fP.
The library
.\" X/Open Curses Issue 7 assumes some optimization will be done, but
.\" does not mandate it in any way.
.I optimizes
its output by computing a minimal volume of operations to mutate the
screen from its state at the previous refresh to the new one.
Effective optimization demands accurate information about the terminal
device:
the management of such information is the province of the
\fB\%terminfo\fP(3X) API,
a feature of every standard
.I curses
implementation.
.PP
Special windows called
.I pads
may also be manipulated.
These are not constrained to the size of the terminal screen and their
contents need not be completely displayed.
See \fB\%curs_pad\fP(3X).
.PP
Many terminals support configuration of character cell foreground and
background colors as well as
.IR attributes ","
which cause characters to render in such modes as
boldfaced,
underlined,
or in reverse video.
See \fB\%curs_attr\fP(3X).
.PP
.I curses
predefines constants for a small set of forms-drawing graphics
corresponding to the DEC Alternate Character Set (ACS),
a feature of VT100 and other terminals.
See \fB\%addch\fP(3X).
.PP
.I curses
is implemented using the operating system's terminal driver;
key events are received not as scan codes but as byte sequences.
Graphical keycaps
(alphanumeric and punctuation keys,
and the space)
appear as-is.
Everything else,
including the tab,
enter/return,
keypad,
arrow,
and function keys,
appears as a control character or a multibyte
.I "escape sequence."
.I curses
can translate the latter into unique
.I "key codes."
See \fB\%keypad\fP(3X) and \fB\%getch\fP(3X).
.PP
.I \%ncurses
provides reimplementations of the SVr4 \fBpanel\fP(3X), \fBform\fP(3X),
and \fBmenu\fP(3X) libraries;
they permit overlapping windows and ease construction of user interfaces
with
.IR curses .
.SS "Initialization"
The selection of an appropriate value of
.I TERM
in the process environment is essential to correct
.I curses
and
.I \%term\%info
library operation.
A well-configured system selects a correct
.I TERM
value automatically;
\fB\%tset\fP(1) may assist with troubleshooting exotic situations.
.PP
If you change the terminal type,
export the shell's
.I TERM
variable,
then run \fB\%tset\fP(1) or the
.RB \*(`` "tput init" \*(''
command.
See subsection \*(``Tabs and Initialization\*('' of \fB\%terminfo\fP(5).
.PP
If the environment variables
.I \%LINES
and
.I \%COLUMNS
are set,
or if the
.I curses
program is executing in a graphical windowing environment,
the information obtained thence overrides that obtained by
.IR \%term\%info .
An
.I \%ncurses
extension supports resizable terminals;
see \fB\%wresize\fP(3X).
.PP
If the environment variable
.I \%TERMINFO
is defined,
a
.I curses
program checks first for a terminal type description in the location it
identifies.
.I \%TERMINFO
is useful for developing type descriptions or when write permission to
.I \%/usr/share/terminfo
is not available.
.PP
See section \*(``ENVIRONMENT\*('' below.
.SS "Naming Conventions"
.I curses
offers many functions in variant forms using a regular set of
alternatives to the name of an elemental one.
Those prefixed with \*(``w\*('' require a
.I \%WINDOW
pointer argument;
those with a \*(``mv\*('' prefix first perform cursor movement using
\fB\%wmove\fP(3X);
a \*(``mvw\*('' prefix indicates both.
The \*(``w\*('' function is typically the elemental one;
the removal of this prefix usually indicates operation on
.BR \%stdscr .
.PP
Four functions prefixed with \*(``p\*('' require a pad argument.
.PP
In function synopses,
.I \%ncurses
man pages apply the following names to parameters.
We introduce the character types in the next subsection.
.PP
.TS
center;
Li L.
bf	a \fIbool\fP (\fBTRUE\fP or \fBFALSE\fP)
c	a \fIchar\fP or \fIint\fP
ch	a \fIchtype\fP
wc	a \fIwchar_t\fP or \fIwint_t\fP
wch	a \fIcchar_t\fP
win	pointer to a \fIWINDOW\fP
pad	pointer to a \fIWINDOW\fP that is a pad
.TE
.SS "Wide and Non-wide Character Configurations"
This man page primarily surveys functions that appear in any
configuration of the library.
There are two common configurations;
see section \*(``ALTERNATE CONFIGURATIONS\*('' below.
.TP 10 \" "ncursesw" + 2n
.I \%ncurses
is the library in its \*(``non-wide\*('' configuration,
handling only eight-bit characters.
It stores a character combined with attributes
and a color pair identifier
in a
.I \%chtype
datum,
which is often an alias of
.IR int .
A string of
.I curses
characters is similar to a C
.I char
string;
a
.I chtype
string ends with an integral
.BR 0 ","
the null
.I curses
character.
.IP
Attributes and a color pair identifier
(with no corresponding character)
can be stored in variables of
.I \%chtype
or
.I \%attr_t
type.
In either case,
they are accessed via an integral bit mask.
.IP
Each cell of a
.I \%WINDOW
is stored as a
.IR \%chtype .
X/Open Curses does not specify the sizes of the character code or
color pair identifier,
nor the quantity of attribute bits,
in
.IR chtype ";"
these are implementation-dependent.
.I \%ncurses
uses eight bits for the character code.
An application requiring a wider character type,
for instance to represent Unicode,
should use the wide-character API.
.TP 10
.I \%ncursesw
is the library in its \*(``wide\*('' configuration,
which handles character encodings requiring a larger data type than
.I \%char
(a byte-sized type)
can represent.
It provides additional functions that complement those in
the non-wide library where the size of the underlying character type is
significant.
A somewhat regular naming convention relates many of the wide variants
to their non-wide counterparts;
where a non-wide function name contains \*(``ch\*('' or \*(``str\*('',
prefix it with \*(``_w\*('' to obtain the wide counterpart.
For example,
\fB\%waddch\fP becomes \fB\%wadd_wch\fP.
(Exceptions that add only \*(``w\*('' comprise
.BR \%addwstr ,
.BR \%inwstr ,
and their variants.)
.\" This is because they operate on "plain" wide-character strings
.\" (`wchar_t*`) and not curses complex character strings (`cchar_t*`).
.\" SVID 4 did specify functions like `addwch()` and `inswch()` that
.\" operated on `chtype`s assuming that they were wide enough for a
.\" `wchar_t` plus attribute and color pair bits; X/Open Curses did not
.\" standardize these.
Another exception is
.B \%ins_nwstr
and its variants,
which is spelled thus instead of \*(``insn_wstr\*(''.
.IP
This convention is inapplicable to some non-wide function names,
so other transformations are used for the wide configuration:
the window background management function \*(``bkgd\*('' becomes
\*(``bkgrnd\*('';
the window border-drawing and -clearing functions are suffixed with
\*(``_set\*('';
and character attribute manipulation functions like
\*(``attron\*('' become \*(``attr_on\*(''.
.RS 10 \" same as foregoing tag width
.TP 9 \" "cchar_t" + 2n
.I \%cchar_t
is a
.I "curses complex character"
and corresponds to the non-wide configuration's
.IR \%chtype .
It is a structure type
because it requires more storage than a standard scalar type offers.
A character code may not be representable as a
.IR \%char ,
and moreover more than one character may occupy a cell
(as with accent marks and other diacritics).
Each character is of type
.IR \%wchar_t ;
a complex character contains one spacing character and zero or more
non-spacing characters
(see below).
A string of complex characters ends with a
.I \%cchar_t
whose
.I \%wchar_t
member is the null wide character.
Attributes and a color pair identifier are stored in separate fields of
the structure,
not combined into an integer as in
.IR \%chtype .
.PP
Each cell of a
.I \%WINDOW
is stored as a
.IR \%cchar_t .
.PP
\fB\%setcchar\fP(3X) and \fB\%getcchar\fP(3X)
store and retrieve
.I \%cchar_t
data.
The wide library API of
.I \%ncurses
depends on two data types standardized by ISO C95.
.TP 9
.I \%wchar_t
stores a wide character.
Like
.IR \%chtype ,
it may be an alias of
.IR int .
Depending on the character encoding,
a wide character may be
.IR spacing ,
meaning that it occupies a character cell by itself and typically
accompanies cursor advancement,
or
.IR non-spacing ,
meaning that it occupies the same cell as a spacing character,
is often regarded as a \*(``modifier\*('' of the base glyph with which
it combines,
and typically does not advance the cursor.
.TP 9
.I \%wint_t
can store a
.I \%wchar_t
or the constant
.BR \%WEOF ,
analogously to the
.IR int -sized
character manipulation functions of ISO C and its constant
.BR \%EOF .
.RE
.\"
.SS "Function Name Index"
The following table lists the
.I curses
functions provided in the non-wide and wide APIs and the corresponding
man pages that describe them.
Those flagged with \*(``*\*(''
are
.IR \%ncurses "-specific,"
neither described by X/Open Curses nor present in SVr4.
.PP
.TS
center tab(/);
l l .
\f(BIcurses\fP Function Name/Man Page
_
COLOR_PAIR/\fBcurs_color\fP(3X)
PAIR_NUMBER/\fBcurs_color\fP(3X)
add_wch/\fBcurs_add_wch\fP(3X)
add_wchnstr/\fBcurs_add_wchstr\fP(3X)
add_wchstr/\fBcurs_add_wchstr\fP(3X)
addch/\fBcurs_addch\fP(3X)
addchnstr/\fBcurs_addchstr\fP(3X)
addchstr/\fBcurs_addchstr\fP(3X)
addnstr/\fBcurs_addstr\fP(3X)
addnwstr/\fBcurs_addwstr\fP(3X)
addstr/\fBcurs_addstr\fP(3X)
addwstr/\fBcurs_addwstr\fP(3X)
alloc_pair/\fBnew_pair\fP(3X)*
assume_default_colors/\fBdefault_colors\fP(3X)*
attr_get/\fBcurs_attr\fP(3X)
attr_off/\fBcurs_attr\fP(3X)
attr_on/\fBcurs_attr\fP(3X)
attr_set/\fBcurs_attr\fP(3X)
attroff/\fBcurs_attr\fP(3X)
attron/\fBcurs_attr\fP(3X)
attrset/\fBcurs_attr\fP(3X)
baudrate/\fBcurs_termattrs\fP(3X)
beep/\fBcurs_beep\fP(3X)
bkgd/\fBcurs_bkgd\fP(3X)
bkgdset/\fBcurs_bkgd\fP(3X)
bkgrnd/\fBcurs_bkgrnd\fP(3X)
bkgrndset/\fBcurs_bkgrnd\fP(3X)
border/\fBcurs_border\fP(3X)
border_set/\fBcurs_border_set\fP(3X)
box/\fBcurs_border\fP(3X)
box_set/\fBcurs_border_set\fP(3X)
can_change_color/\fBcurs_color\fP(3X)
cbreak/\fBcurs_inopts\fP(3X)
chgat/\fBcurs_attr\fP(3X)
clear/\fBcurs_clear\fP(3X)
clearok/\fBcurs_outopts\fP(3X)
clrtobot/\fBcurs_clear\fP(3X)
clrtoeol/\fBcurs_clear\fP(3X)
color_content/\fBcurs_color\fP(3X)
color_set/\fBcurs_attr\fP(3X)
copywin/\fBcurs_overlay\fP(3X)
curs_set/\fBcurs_kernel\fP(3X)
curses_trace/\fBcurs_trace\fP(3X)*
curses_version/\fBcurs_extend\fP(3X)*
def_prog_mode/\fBcurs_kernel\fP(3X)
def_shell_mode/\fBcurs_kernel\fP(3X)
define_key/\fBdefine_key\fP(3X)*
del_curterm/\fBcurs_terminfo\fP(3X)
delay_output/\fBcurs_util\fP(3X)
delch/\fBcurs_delch\fP(3X)
deleteln/\fBcurs_deleteln\fP(3X)
delscreen/\fBcurs_initscr\fP(3X)
delwin/\fBcurs_window\fP(3X)
derwin/\fBcurs_window\fP(3X)
doupdate/\fBcurs_refresh\fP(3X)
dupwin/\fBcurs_window\fP(3X)
echo/\fBcurs_inopts\fP(3X)
echo_wchar/\fBcurs_add_wch\fP(3X)
echochar/\fBcurs_addch\fP(3X)
endwin/\fBcurs_initscr\fP(3X)
erase/\fBcurs_clear\fP(3X)
erasechar/\fBcurs_termattrs\fP(3X)
erasewchar/\fBcurs_termattrs\fP(3X)
exit_curses/\fBcurs_memleaks\fP(3X)*
exit_terminfo/\fBcurs_memleaks\fP(3X)*
extended_color_content/\fBcurs_color\fP(3X)*
extended_pair_content/\fBcurs_color\fP(3X)*
extended_slk_color/\fBcurs_slk\fP(3X)*
filter/\fBcurs_util\fP(3X)
find_pair/\fBnew_pair\fP(3X)*
flash/\fBcurs_beep\fP(3X)
flushinp/\fBcurs_util\fP(3X)
free_pair/\fBnew_pair\fP(3X)*
get_escdelay/\fBcurs_threads\fP(3X)*
get_wch/\fBcurs_get_wch\fP(3X)
get_wstr/\fBcurs_get_wstr\fP(3X)
getattrs/\fBcurs_attr\fP(3X)
getbegx/\fBcurs_legacy\fP(3X)*
getbegy/\fBcurs_legacy\fP(3X)*
getbegyx/\fBcurs_getyx\fP(3X)
getbkgd/\fBcurs_bkgd\fP(3X)
getbkgrnd/\fBcurs_bkgrnd\fP(3X)
getcchar/\fBcurs_getcchar\fP(3X)
getch/\fBcurs_getch\fP(3X)
getcurx/\fBcurs_legacy\fP(3X)*
getcury/\fBcurs_legacy\fP(3X)*
getmaxx/\fBcurs_legacy\fP(3X)*
getmaxy/\fBcurs_legacy\fP(3X)*
getmaxyx/\fBcurs_getyx\fP(3X)
getmouse/\fBcurs_mouse\fP(3X)*
getn_wstr/\fBcurs_get_wstr\fP(3X)
getnstr/\fBcurs_getstr\fP(3X)
getparx/\fBcurs_legacy\fP(3X)*
getpary/\fBcurs_legacy\fP(3X)*
getparyx/\fBcurs_getyx\fP(3X)
getstr/\fBcurs_getstr\fP(3X)
getsyx/\fBcurs_kernel\fP(3X)
getwin/\fBcurs_util\fP(3X)
getyx/\fBcurs_getyx\fP(3X)
halfdelay/\fBcurs_inopts\fP(3X)
has_colors/\fBcurs_color\fP(3X)
has_ic/\fBcurs_termattrs\fP(3X)
has_il/\fBcurs_termattrs\fP(3X)
has_key/\fBcurs_getch\fP(3X)*
has_mouse/\fBcurs_mouse\fP(3X)*
hline/\fBcurs_border\fP(3X)
hline_set/\fBcurs_border_set\fP(3X)
idcok/\fBcurs_outopts\fP(3X)
idlok/\fBcurs_outopts\fP(3X)
immedok/\fBcurs_outopts\fP(3X)
in_wch/\fBcurs_in_wch\fP(3X)
in_wchnstr/\fBcurs_in_wchstr\fP(3X)
in_wchstr/\fBcurs_in_wchstr\fP(3X)
inch/\fBcurs_inch\fP(3X)
inchnstr/\fBcurs_inchstr\fP(3X)
inchstr/\fBcurs_inchstr\fP(3X)
init_color/\fBcurs_color\fP(3X)
init_extended_color/\fBcurs_color\fP(3X)*
init_extended_pair/\fBcurs_color\fP(3X)*
init_pair/\fBcurs_color\fP(3X)
initscr/\fBcurs_initscr\fP(3X)
innstr/\fBcurs_instr\fP(3X)
innwstr/\fBcurs_inwstr\fP(3X)
ins_nwstr/\fBcurs_ins_wstr\fP(3X)
ins_wch/\fBcurs_ins_wch\fP(3X)
ins_wstr/\fBcurs_ins_wstr\fP(3X)
insch/\fBcurs_insch\fP(3X)
insdelln/\fBcurs_deleteln\fP(3X)
insertln/\fBcurs_deleteln\fP(3X)
insnstr/\fBcurs_insstr\fP(3X)
insstr/\fBcurs_insstr\fP(3X)
instr/\fBcurs_instr\fP(3X)
intrflush/\fBcurs_inopts\fP(3X)
inwstr/\fBcurs_inwstr\fP(3X)
is_cbreak/\fBcurs_inopts\fP(3X)*
is_cleared/\fBcurs_opaque\fP(3X)*
is_echo/\fBcurs_inopts\fP(3X)*
is_idcok/\fBcurs_opaque\fP(3X)*
is_idlok/\fBcurs_opaque\fP(3X)*
is_immedok/\fBcurs_opaque\fP(3X)*
is_keypad/\fBcurs_opaque\fP(3X)*
is_leaveok/\fBcurs_opaque\fP(3X)*
is_linetouched/\fBcurs_touch\fP(3X)
is_nl/\fBcurs_inopts\fP(3X)*
is_nodelay/\fBcurs_opaque\fP(3X)*
is_notimeout/\fBcurs_opaque\fP(3X)*
is_pad/\fBcurs_opaque\fP(3X)*
is_raw/\fBcurs_inopts\fP(3X)*
is_scrollok/\fBcurs_opaque\fP(3X)*
is_subwin/\fBcurs_opaque\fP(3X)*
is_syncok/\fBcurs_opaque\fP(3X)*
is_term_resized/\fBresizeterm\fP(3X)*
is_wintouched/\fBcurs_touch\fP(3X)
isendwin/\fBcurs_initscr\fP(3X)
key_defined/\fBkey_defined\fP(3X)*
key_name/\fBcurs_util\fP(3X)
keybound/\fBkeybound\fP(3X)*
keyname/\fBcurs_util\fP(3X)
keyok/\fBkeyok\fP(3X)*
keypad/\fBcurs_inopts\fP(3X)
killchar/\fBcurs_termattrs\fP(3X)
killwchar/\fBcurs_termattrs\fP(3X)
leaveok/\fBcurs_outopts\fP(3X)
longname/\fBcurs_termattrs\fP(3X)
mcprint/\fBcurs_print\fP(3X)*
meta/\fBcurs_inopts\fP(3X)
mouse_trafo/\fBcurs_mouse\fP(3X)*
mouseinterval/\fBcurs_mouse\fP(3X)*
mousemask/\fBcurs_mouse\fP(3X)*
move/\fBcurs_move\fP(3X)
mvadd_wch/\fBcurs_add_wch\fP(3X)
mvadd_wchnstr/\fBcurs_add_wchstr\fP(3X)
mvadd_wchstr/\fBcurs_add_wchstr\fP(3X)
mvaddch/\fBcurs_addch\fP(3X)
mvaddchnstr/\fBcurs_addchstr\fP(3X)
mvaddchstr/\fBcurs_addchstr\fP(3X)
mvaddnstr/\fBcurs_addstr\fP(3X)
mvaddnwstr/\fBcurs_addwstr\fP(3X)
mvaddstr/\fBcurs_addstr\fP(3X)
mvaddwstr/\fBcurs_addwstr\fP(3X)
mvchgat/\fBcurs_attr\fP(3X)
mvcur/\fBcurs_kernel\fP(3X)
mvdelch/\fBcurs_delch\fP(3X)
mvderwin/\fBcurs_window\fP(3X)
mvget_wch/\fBcurs_get_wch\fP(3X)
mvget_wstr/\fBcurs_get_wstr\fP(3X)
mvgetch/\fBcurs_getch\fP(3X)
mvgetn_wstr/\fBcurs_get_wstr\fP(3X)
mvgetnstr/\fBcurs_getstr\fP(3X)
mvgetstr/\fBcurs_getstr\fP(3X)
mvhline/\fBcurs_border\fP(3X)
mvhline_set/\fBcurs_border_set\fP(3X)
mvin_wch/\fBcurs_in_wch\fP(3X)
mvin_wchnstr/\fBcurs_in_wchstr\fP(3X)
mvin_wchstr/\fBcurs_in_wchstr\fP(3X)
mvinch/\fBcurs_inch\fP(3X)
mvinchnstr/\fBcurs_inchstr\fP(3X)
mvinchstr/\fBcurs_inchstr\fP(3X)
mvinnstr/\fBcurs_instr\fP(3X)
mvinnwstr/\fBcurs_inwstr\fP(3X)
mvins_nwstr/\fBcurs_ins_wstr\fP(3X)
mvins_wch/\fBcurs_ins_wch\fP(3X)
mvins_wstr/\fBcurs_ins_wstr\fP(3X)
mvinsch/\fBcurs_insch\fP(3X)
mvinsnstr/\fBcurs_insstr\fP(3X)
mvinsstr/\fBcurs_insstr\fP(3X)
mvinstr/\fBcurs_instr\fP(3X)
mvinwstr/\fBcurs_inwstr\fP(3X)
mvprintw/\fBcurs_printw\fP(3X)
mvscanw/\fBcurs_scanw\fP(3X)
mvvline/\fBcurs_border\fP(3X)
mvvline_set/\fBcurs_border_set\fP(3X)
mvwadd_wch/\fBcurs_add_wch\fP(3X)
mvwadd_wchnstr/\fBcurs_add_wchstr\fP(3X)
mvwadd_wchstr/\fBcurs_add_wchstr\fP(3X)
mvwaddch/\fBcurs_addch\fP(3X)
mvwaddchnstr/\fBcurs_addchstr\fP(3X)
mvwaddchstr/\fBcurs_addchstr\fP(3X)
mvwaddnstr/\fBcurs_addstr\fP(3X)
mvwaddnwstr/\fBcurs_addwstr\fP(3X)
mvwaddstr/\fBcurs_addstr\fP(3X)
mvwaddwstr/\fBcurs_addwstr\fP(3X)
mvwchgat/\fBcurs_attr\fP(3X)
mvwdelch/\fBcurs_delch\fP(3X)
mvwget_wch/\fBcurs_get_wch\fP(3X)
mvwget_wstr/\fBcurs_get_wstr\fP(3X)
mvwgetch/\fBcurs_getch\fP(3X)
mvwgetn_wstr/\fBcurs_get_wstr\fP(3X)
mvwgetnstr/\fBcurs_getstr\fP(3X)
mvwgetstr/\fBcurs_getstr\fP(3X)
mvwhline/\fBcurs_border\fP(3X)
mvwhline_set/\fBcurs_border_set\fP(3X)
mvwin/\fBcurs_window\fP(3X)
mvwin_wch/\fBcurs_in_wch\fP(3X)
mvwin_wchnstr/\fBcurs_in_wchstr\fP(3X)
mvwin_wchstr/\fBcurs_in_wchstr\fP(3X)
mvwinch/\fBcurs_inch\fP(3X)
mvwinchnstr/\fBcurs_inchstr\fP(3X)
mvwinchstr/\fBcurs_inchstr\fP(3X)
mvwinnstr/\fBcurs_instr\fP(3X)
mvwinnwstr/\fBcurs_inwstr\fP(3X)
mvwins_nwstr/\fBcurs_ins_wstr\fP(3X)
mvwins_wch/\fBcurs_ins_wch\fP(3X)
mvwins_wstr/\fBcurs_ins_wstr\fP(3X)
mvwinsch/\fBcurs_insch\fP(3X)
mvwinsnstr/\fBcurs_insstr\fP(3X)
mvwinsstr/\fBcurs_insstr\fP(3X)
mvwinstr/\fBcurs_instr\fP(3X)
mvwinwstr/\fBcurs_inwstr\fP(3X)
mvwprintw/\fBcurs_printw\fP(3X)
mvwscanw/\fBcurs_scanw\fP(3X)
mvwvline/\fBcurs_border\fP(3X)
mvwvline_set/\fBcurs_border_set\fP(3X)
napms/\fBcurs_kernel\fP(3X)
newpad/\fBcurs_pad\fP(3X)
newterm/\fBcurs_initscr\fP(3X)
newwin/\fBcurs_window\fP(3X)
nl/\fBcurs_inopts\fP(3X)
nocbreak/\fBcurs_inopts\fP(3X)
nodelay/\fBcurs_inopts\fP(3X)
noecho/\fBcurs_inopts\fP(3X)
nofilter/\fBcurs_util\fP(3X)*
nonl/\fBcurs_inopts\fP(3X)
noqiflush/\fBcurs_inopts\fP(3X)
noraw/\fBcurs_inopts\fP(3X)
notimeout/\fBcurs_inopts\fP(3X)
overlay/\fBcurs_overlay\fP(3X)
overwrite/\fBcurs_overlay\fP(3X)
pair_content/\fBcurs_color\fP(3X)
pecho_wchar/\fBcurs_pad\fP(3X)
pechochar/\fBcurs_pad\fP(3X)
pnoutrefresh/\fBcurs_pad\fP(3X)
prefresh/\fBcurs_pad\fP(3X)
printw/\fBcurs_printw\fP(3X)
putp/\fBcurs_terminfo\fP(3X)
putwin/\fBcurs_util\fP(3X)
qiflush/\fBcurs_inopts\fP(3X)
raw/\fBcurs_inopts\fP(3X)
redrawwin/\fBcurs_refresh\fP(3X)
refresh/\fBcurs_refresh\fP(3X)
reset_color_pairs/\fBcurs_color\fP(3X)*
reset_prog_mode/\fBcurs_kernel\fP(3X)
reset_shell_mode/\fBcurs_kernel\fP(3X)
resetty/\fBcurs_kernel\fP(3X)
resize_term/\fBresizeterm\fP(3X)*
resizeterm/\fBresizeterm\fP(3X)*
restartterm/\fBcurs_terminfo\fP(3X)
ripoffline/\fBcurs_kernel\fP(3X)
savetty/\fBcurs_kernel\fP(3X)
scanw/\fBcurs_scanw\fP(3X)
scr_dump/\fBcurs_scr_dump\fP(3X)
scr_init/\fBcurs_scr_dump\fP(3X)
scr_restore/\fBcurs_scr_dump\fP(3X)
scr_set/\fBcurs_scr_dump\fP(3X)
scrl/\fBcurs_scroll\fP(3X)
scroll/\fBcurs_scroll\fP(3X)
scrollok/\fBcurs_outopts\fP(3X)
set_curterm/\fBcurs_terminfo\fP(3X)
set_escdelay/\fBcurs_threads\fP(3X)*
set_tabsize/\fBcurs_threads\fP(3X)*
set_term/\fBcurs_initscr\fP(3X)
setcchar/\fBcurs_getcchar\fP(3X)
setscrreg/\fBcurs_outopts\fP(3X)
setsyx/\fBcurs_kernel\fP(3X)
setupterm/\fBcurs_terminfo\fP(3X)
slk_attr/\fBcurs_slk\fP(3X)*
slk_attr_off/\fBcurs_slk\fP(3X)
slk_attr_on/\fBcurs_slk\fP(3X)
slk_attr_set/\fBcurs_slk\fP(3X)
slk_attroff/\fBcurs_slk\fP(3X)
slk_attron/\fBcurs_slk\fP(3X)
slk_attrset/\fBcurs_slk\fP(3X)
slk_clear/\fBcurs_slk\fP(3X)
slk_color/\fBcurs_slk\fP(3X)
slk_init/\fBcurs_slk\fP(3X)
slk_label/\fBcurs_slk\fP(3X)
slk_noutrefresh/\fBcurs_slk\fP(3X)
slk_refresh/\fBcurs_slk\fP(3X)
slk_restore/\fBcurs_slk\fP(3X)
slk_set/\fBcurs_slk\fP(3X)
slk_touch/\fBcurs_slk\fP(3X)
slk_wset/\fBcurs_slk\fP(3X)
standend/\fBcurs_attr\fP(3X)
standout/\fBcurs_attr\fP(3X)
start_color/\fBcurs_color\fP(3X)
subpad/\fBcurs_pad\fP(3X)
subwin/\fBcurs_window\fP(3X)
syncok/\fBcurs_window\fP(3X)
term_attrs/\fBcurs_termattrs\fP(3X)
termattrs/\fBcurs_termattrs\fP(3X)
termname/\fBcurs_termattrs\fP(3X)
tgetent/\fBcurs_termcap\fP(3X)
tgetflag/\fBcurs_termcap\fP(3X)
tgetnum/\fBcurs_termcap\fP(3X)
tgetstr/\fBcurs_termcap\fP(3X)
tgoto/\fBcurs_termcap\fP(3X)
tigetflag/\fBcurs_terminfo\fP(3X)
tigetnum/\fBcurs_terminfo\fP(3X)
tigetstr/\fBcurs_terminfo\fP(3X)
timeout/\fBcurs_inopts\fP(3X)
tiparm/\fBcurs_terminfo\fP(3X)
tiparm_s/\fBcurs_terminfo\fP(3X)*
tiscan_s/\fBcurs_terminfo\fP(3X)*
touchline/\fBcurs_touch\fP(3X)
touchwin/\fBcurs_touch\fP(3X)
tparm/\fBcurs_terminfo\fP(3X)
tputs/\fBcurs_termcap\fP(3X)
tputs/\fBcurs_terminfo\fP(3X)
trace/\fBcurs_trace\fP(3X)*
typeahead/\fBcurs_inopts\fP(3X)
unctrl/\fBcurs_util\fP(3X)
unget_wch/\fBcurs_get_wch\fP(3X)
ungetch/\fBcurs_getch\fP(3X)
ungetmouse/\fBcurs_mouse\fP(3X)*
untouchwin/\fBcurs_touch\fP(3X)
use_default_colors/\fBdefault_colors\fP(3X)*
use_env/\fBcurs_util\fP(3X)
use_extended_names/\fBcurs_extend\fP(3X)*
use_legacy_coding/\fBlegacy_coding\fP(3X)*
use_screen/\fBcurs_threads\fP(3X)*
use_tioctl/\fBcurs_util\fP(3X)*
use_window/\fBcurs_threads\fP(3X)*
vid_attr/\fBcurs_terminfo\fP(3X)
vid_puts/\fBcurs_terminfo\fP(3X)
vidattr/\fBcurs_terminfo\fP(3X)
vidputs/\fBcurs_terminfo\fP(3X)
vline/\fBcurs_border\fP(3X)
vline_set/\fBcurs_border_set\fP(3X)
vw_printw/\fBcurs_printw\fP(3X)
vw_scanw/\fBcurs_scanw\fP(3X)
vwprintw/\fBcurs_printw\fP(3X)
vwscanw/\fBcurs_scanw\fP(3X)
wadd_wch/\fBcurs_add_wch\fP(3X)
wadd_wchnstr/\fBcurs_add_wchstr\fP(3X)
wadd_wchstr/\fBcurs_add_wchstr\fP(3X)
waddch/\fBcurs_addch\fP(3X)
waddchnstr/\fBcurs_addchstr\fP(3X)
waddchstr/\fBcurs_addchstr\fP(3X)
waddnstr/\fBcurs_addstr\fP(3X)
waddnwstr/\fBcurs_addwstr\fP(3X)
waddstr/\fBcurs_addstr\fP(3X)
waddwstr/\fBcurs_addwstr\fP(3X)
wattr_get/\fBcurs_attr\fP(3X)
wattr_off/\fBcurs_attr\fP(3X)
wattr_on/\fBcurs_attr\fP(3X)
wattr_set/\fBcurs_attr\fP(3X)
wattroff/\fBcurs_attr\fP(3X)
wattron/\fBcurs_attr\fP(3X)
wattrset/\fBcurs_attr\fP(3X)
wbkgd/\fBcurs_bkgd\fP(3X)
wbkgdset/\fBcurs_bkgd\fP(3X)
wbkgrnd/\fBcurs_bkgrnd\fP(3X)
wbkgrndset/\fBcurs_bkgrnd\fP(3X)
wborder/\fBcurs_border\fP(3X)
wborder_set/\fBcurs_border_set\fP(3X)
wchgat/\fBcurs_attr\fP(3X)
wclear/\fBcurs_clear\fP(3X)
wclrtobot/\fBcurs_clear\fP(3X)
wclrtoeol/\fBcurs_clear\fP(3X)
wcolor_set/\fBcurs_attr\fP(3X)
wcursyncup/\fBcurs_window\fP(3X)
wdelch/\fBcurs_delch\fP(3X)
wdeleteln/\fBcurs_deleteln\fP(3X)
wecho_wchar/\fBcurs_add_wch\fP(3X)
wechochar/\fBcurs_addch\fP(3X)
wenclose/\fBcurs_mouse\fP(3X)*
werase/\fBcurs_clear\fP(3X)
wget_wch/\fBcurs_get_wch\fP(3X)
wget_wstr/\fBcurs_get_wstr\fP(3X)
wgetbkgrnd/\fBcurs_bkgrnd\fP(3X)
wgetch/\fBcurs_getch\fP(3X)
wgetdelay/\fBcurs_opaque\fP(3X)*
wgetn_wstr/\fBcurs_get_wstr\fP(3X)
wgetnstr/\fBcurs_getstr\fP(3X)
wgetparent/\fBcurs_opaque\fP(3X)*
wgetscrreg/\fBcurs_opaque\fP(3X)*
wgetstr/\fBcurs_getstr\fP(3X)
whline/\fBcurs_border\fP(3X)
whline_set/\fBcurs_border_set\fP(3X)
win_wch/\fBcurs_in_wch\fP(3X)
win_wchnstr/\fBcurs_in_wchstr\fP(3X)
win_wchstr/\fBcurs_in_wchstr\fP(3X)
winch/\fBcurs_inch\fP(3X)
winchnstr/\fBcurs_inchstr\fP(3X)
winchstr/\fBcurs_inchstr\fP(3X)
winnstr/\fBcurs_instr\fP(3X)
winnwstr/\fBcurs_inwstr\fP(3X)
wins_nwstr/\fBcurs_ins_wstr\fP(3X)
wins_wch/\fBcurs_ins_wch\fP(3X)
wins_wstr/\fBcurs_ins_wstr\fP(3X)
winsch/\fBcurs_insch\fP(3X)
winsdelln/\fBcurs_deleteln\fP(3X)
winsertln/\fBcurs_deleteln\fP(3X)
winsnstr/\fBcurs_insstr\fP(3X)
winsstr/\fBcurs_insstr\fP(3X)
winstr/\fBcurs_instr\fP(3X)
winwstr/\fBcurs_inwstr\fP(3X)
wmouse_trafo/\fBcurs_mouse\fP(3X)*
wmove/\fBcurs_move\fP(3X)
wnoutrefresh/\fBcurs_refresh\fP(3X)
wprintw/\fBcurs_printw\fP(3X)
wredrawln/\fBcurs_refresh\fP(3X)
wrefresh/\fBcurs_refresh\fP(3X)
wresize/\fBwresize\fP(3X)*
wscanw/\fBcurs_scanw\fP(3X)
wscrl/\fBcurs_scroll\fP(3X)
wsetscrreg/\fBcurs_outopts\fP(3X)
wstandend/\fBcurs_attr\fP(3X)
wstandout/\fBcurs_attr\fP(3X)
wsyncdown/\fBcurs_window\fP(3X)
wsyncup/\fBcurs_window\fP(3X)
wtimeout/\fBcurs_inopts\fP(3X)
wtouchln/\fBcurs_touch\fP(3X)
wunctrl/\fBcurs_util\fP(3X)
wvline/\fBcurs_border\fP(3X)
wvline_set/\fBcurs_border_set\fP(3X)
.TE
.PP
.IR \%ncurses 's
.I "screen-pointer extension"
adds additional functions corresponding to many of the above,
each with an \*(``_sp\*('' suffix;
see \fBcurs_sp_funcs\fP(3X).
.PP
The availability of some extensions is configurable when
.I \%ncurses
is compiled;
see sections \*(``ALTERNATE CONFIGURATIONS\*('' and \*(``EXTENSIONS\*(''
below.
.SH RETURN VALUE
Unless otherwise noted,
functions that return integers return the constants
.B OK
on success and
.B ERR
on failure;
see \fB\%curs_variables\fP(3X).
Functions that return pointers return
.B NULL
on failure.
Typically,
.I \%ncurses
treats a null pointer passed as a function parameter as a failure.
Functions prefixed with \*(``mv\*('' first perform cursor movement and
fail if the position
.RI ( y ,
.IR x )
is outside the window boundaries.
.SH ENVIRONMENT
The following symbols from the process environment customize the
runtime behavior of
.I \%ncurses
applications.
The library may be configured to disregard the variables
.IR \%TERMINFO ,
.IR \%TERMINFO_DIRS ,
.IR \%TERMPATH ,
and
.IR HOME ,
if the user is the superuser (root),
or the application uses \fI\%setuid\fP(2) or \fI\%setgid\fP(2).
.SS "\fIBAUDRATE\fP"
The debugging library checks this variable when the application has
redirected output to a file.
Its integral value is used for the baud rate.
If that value is absent or invalid,
.I \%ncurses
uses 9600.
This feature allows developers to construct repeatable test cases
that take into account optimization decisions that depend
on the terminal's line speed.
.SS "\fICC\fP (command character)"
When set,
the
.B \%command_character
.RB \%( cmdch )
capability value of loaded
.I \%term\%info
entries changes to the value of this variable.
Very few
.I \%term\%info
entries provide this feature.
.PP
Because this name is also used in development environments to store the
C compiler's name,
.I \%ncurses
ignores its value if it is not one character in length.
.SS "\fICOLUMNS\fP"
This variable specifies the width of the screen in characters.
Applications running in a windowing environment usually are able to
obtain the width of the window in which they are executing.
If
.I \%COLUMNS
is not defined and the terminal's screen size is not available from the
terminal driver,
.I \%ncurses
uses the size specified by the
.B \%columns
.RB \%( cols )
capability of the terminal type's entry in the
.I \%term\%info
database,
if any.
.PP
It is important that your application use the correct screen size.
Automatic detection thereof is not always possible because an
application may be running on a host that does not honor NAWS
(Negotiations About Window Size)
or as a different user ID than the owner of the terminal device file.
Setting
.I \%COLUMNS
and/or
.I \%LINES
overrides the library's use of the screen size obtained from the
operating system.
.PP
The
.I \%COLUMNS
and
.I \%LINES
variables may be specified independently.
.I \%ncurses
enforces an upper limit of 512 on each when reading the value.
This property is useful to circumvent misfeatures of legacy terminal
type descriptions;
\fI\%xterm\fP(1) descriptions specifying 65 lines were once notorious.
For best results,
avoid specifying
.B cols
and
.B lines
capability codes in
.I \%term\%info
descriptions of terminal emulators.
.PP
\fBuse_env\fP(3X) can disable use of the process environment
in determining the screen size.
\fBuse_tioctl\fP(3X) can update
.I \%COLUMNS
and
.I \%LINES
to match the screen size obtained from system calls or the terminal
database.
.SS "\fIESCDELAY\fP"
For
.I curses
to distinguish the ESC character resulting from a user's press of the
\*(``Escape\*('' key on the input device from one beginning an
.I "escape sequence"
(as commonly produced by function keys),
it waits after receiving the escape character to see if further
characters are available on the input stream within a short interval.
A global variable
.B \%ESCDELAY
stores this interval in milliseconds.
The default value of 1000
(one second)
is adequate for most uses.
This environment variable overrides it;
.I \%ncurses
enforces an upper limit of 30,000
(30 seconds)
when reading the value.
.PP
The most common instance where you may wish to change this value
is to work with a remote host over a slow communication channel.
If the host running a
.I curses
application does not receive the characters of an escape sequence in a
timely manner,
the library can interpret them as multiple key stroke events.
.PP
\fI\%xterm\fP(1) mouse events are a form of escape sequence;
therefore,
if your application makes heavy use of multiple-clicking,
you may wish to lengthen the default value because the delay applies
to the composite multi-click event as well as the individual clicks.
.PP
Portable applications should not rely upon the presence of
.B \%ESCDELAY
in either form,
but setting the environment variable rather than the global variable
does not create problems when compiling an application.
.PP
If \fB\%keypad\fP(3X) is disabled for the
.I curses
window receiving input,
a program must disambiguate escape sequences itself.
.SS "\fIHOME\fP"
.I \%ncurses
may read and write auxiliary terminal descriptions in
.I \%.termcap
and
.I \%.terminfo
files in the user's home directory.
.SS "\fILINES\fP"
This counterpart to
.I \%COLUMNS
specifies the height of the screen in characters.
The corresponding
.I \%term\%info
capability and code is
.BR \%lines .
See the description of the
.I \%COLUMNS
variable above.
.SS "\fIMOUSE_BUTTONS_123\fP"
(OS/2 EMX port only)
OS/2 numbers a three-button mouse inconsistently with other platforms,
such that 1 is the left button,
2 the right,
and 3 the middle.
This variable customizes the mouse button numbering.
Its value must be three digits 1\-3 in any order.
By default,
.I \%ncurses
assumes a numbering of \*(``132\*(''.
.SS "\fINCURSES_ASSUMED_COLORS\fP"
If set,
this variable overrides the
.I \%ncurses
library's compiled-in assumption that the terminal's default colors are
white on black;
see \fB\%default_colors\fP(3X).
Set the foreground and background color values with this environment
variable by assigning it two integer values separated by a comma,
indicating foregound and background color numbers,
respectively.
.PP
For example,
to tell
.I \%ncurses
not to assume anything about the colors,
use a value of \*(``\-1,\-1\*(''.
To make the default color scheme green on black,
use \*(``2,0\*(''.
.I \%ncurses
accepts integral values from \-1 up to the value of the
.I \%term\%info
.B \%max_colors
.RB ( colors )
capability.
.SS "\fINCURSES_CONSOLE2\fP"
(MinGW port only)
The
.I \%Console2
.\" https://www.hanselman.com/blog/console2-a-better-windows-command-prompt
program defectively handles the Microsoft Console API call
.IR \%Create\%Console\%Screen\%Buffer .
Applications that use it will hang.
However,
it is possible to simulate the action of this call by mapping
coordinates,
explicitly saving and restoring the original screen contents.
Setting the environment variable
.I \%NCGDB
has the same effect.
.SS "\fINCURSES_GPM_TERMS\fP"
(Linux only)
When
.I \%ncurses
is configured to use the GPM interface,
this variable may list one or more terminal type names,
delimited by vertical bars
.RB ( | )
or colons
.RB ( : ),
against which the
.I TERM
variable
(see below)
is matched.
An empty value disables the GPM interface,
using
.IR \%ncurses 's
built-in support for \fI\%xterm\fP(1) mouse protocols instead.
If the variable is absent,
.I \%ncurses
attempts to open GPM if
.I TERM
contains \*(``linux\*(''.
.SS "\fINCURSES_NO_HARD_TABS\fP"
.I \%ncurses
may use tab characters in cursor movement optimization.
In some cases,
your terminal driver may not handle them properly.
Set this environment variable to any value to disable the feature.
You can also adjust your \fI\%stty\fP(1) settings to avoid the problem.
.SS "\fINCURSES_NO_MAGIC_COOKIE\fP"
Many terminals store video attributes as a property of a character cell,
as
.I curses
does.
Historically,
some recorded changes in video attributes as data that logically
.I occupies
character cells on the display,
switching attributes on or off,
similarly to tags in a markup language;
these are termed \*(``magic cookies\*('',
and must be subsequently overprinted.
If the
.I \%term\%info
entry for your terminal type does not adequately describe its handling
of magic cookies,
set this variable to any value to instruct
.I \%ncurses
to disable attributes entirely.
.SS "\fINCURSES_NO_PADDING\fP"
Most terminal type descriptions in the
.I \%term\%info
database detail hardware devices.
Many people use
.IR curses -based
applications in terminal emulator programs that run in a windowing
environment.
These programs can duplicate all of the important features of a hardware
terminal,
but often lack their limitations.
Chief among these absent drawbacks is the problem of data flow
management;
that is,
limiting the speed of communication to what the hardware could handle.
Unless a hardware terminal is interfaced into a terminal concentrator
(which does flow control),
an application must manage flow itself to prevent overruns and data
loss.
.PP
A solution that comes at no hardware cost is for an application to pause
after directing a terminal to execute an operation that it performs
slowly,
such as clearing the display.
Many terminal type descriptions,
including that for the VT100,
embed delay specifications in capabilities.
You may wish to use these terminal descriptions without paying the
performance penalty.
Set
.I \%NCURSES_NO_PADDING
to any value to disable all but mandatory padding.
Mandatory padding is used by such terminal capabilities as
.B \%flash_screen
.RB ( flash ).
.SS "\fINCURSES_NO_SETBUF\fP"
(Obsolete)
Prior to internal changes developed in
.I \%ncurses
5.9
(patches 20120825 through 20130126),
the library used \fI\%setbuf\fP(3) to enable fully buffered output when
initializing the terminal.
This was done,
as in SVr4
.IR curses ,
to increase performance.
For testing purposes,
both of
.I \%ncurses
and of certain applications,
this feature was made optional.
Setting this variable disabled output buffering,
leaving the output stream in the original
(usually line-buffered)
mode.
.PP
Nowadays,
.I \%ncurses
performs its own buffering and does not require this workaround;
it does not modify the buffering of the standard output stream.
This approach makes signal handling,
as for interrupts,
more robust.
A drawback is that certain unconventional programs mixed
\fI\%stdio\fP(3) calls with
.I \%ncurses
calls and (usually)
got the behavior they expected.
This is no longer the case;
.I \%ncurses
does not write to the standard output file descriptor through a
.IR stdio -buffered
stream.
.PP
As a special case,
low-level API calls such as \fB\%putp\fP(3X) still use the
standard output stream.
High-level
.I curses
calls such as \fB\%printw\fP(3X) do not.
.SS "\fINCURSES_NO_UTF8_ACS\fP"
At initialization,
.I \%ncurses
inspects the
.I TERM
environment variable for special cases where VT100 forms-drawing
characters
(and the corresponding alternate character set
.I \%term\%info
capabilities)
are known to be unsupported by terminal types that otherwise claim VT100
compatibility.
Specifically,
when running in a UTF-8 locale,
the Linux virtual console device and the GNU \fI\%screen\fP(1)
program ignore them.
Set this variable to a nonzero value to instruct
.I \%ncurses
that the terminal's ACS support is broken;
the library then outputs Unicode code points that correspond to the
forms-drawing
characters.
Set it to zero
(or a non-integer)
to disable the special check for terminal type names matching
\*(``linux\*('' or \*(``screen\*('',
directing
.I \%ncurses
to assume that the ACS feature works if the terminal type description
advertises it.
.PP
As an alternative to use of this variable,
.I \%ncurses
checks for an extended
.I \%term\%info
numeric capability \fBU8\fP
that can be compiled using
.RB \*(`` "tic \-x" \*(''.
Examples follow.
.PP
.RS 3
.EX
# linux console, if patched to provide working
# VT100 shift\-in/shift\-out, with corresponding font.
linux\-vt100|linux console with VT100 line\-graphics,
        U8#0, use=linux,
\&
# uxterm with vt100Graphics resource set to false
xterm\-utf8|xterm relying on UTF\-8 line\-graphics,
        U8#1, use=xterm,
.EE
.RE
.PP
The two-character name \*(``U8\*('' was chosen to permit its use via
.IR \%ncurses 's
.I termcap
interface.
.SS "\fINCURSES_TRACE\fP"
At initialization,
.I \%ncurses
(in its debugging configuration)
checks for this variable's presence.
If defined with an integral value,
the library calls \fB\%curses_trace\fP(3X) with that value as the
argument.
.SS "\fITERM\fP"
The
.I TERM
variable denotes the terminal type.
Each is distinct,
though many are similar.
It is commonly set by terminal emulators to help applications find a
workable terminal description.
Some choose a popular approximation such as \*(``ansi\*('',
\*(``vt100\*('', or \*(``xterm\*('' rather than an exact fit to their
capabilities.
Not infrequently,
an application will have problems with that approach;
for example,
a key stroke may not operate correctly,
or produce no effect but seeming garbage characters on the screen.
.PP
Setting
.I TERM
has no effect on hardware operation;
it affects the way applications communicate with the terminal.
Likewise,
as a general rule
(\fIxterm\fP(1) being a rare exception),
terminal emulators that allow you to specify
.I TERM
as a parameter or configuration value do not change their behavior to
match that setting.
.SS "\fITERMCAP\fP"
If
.I \%ncurses
is configured with
.I termcap
support,
it checks for a terminal type description in
.I termcap
format if one in
.I \%term\%info
format is not available.
Setting this variable directs
.I \%ncurses
to ignore the usual
.I termcap
database location,
.IR \%/etc/termcap ;
see
.I \%TERMPATH
below.
.I \%TERMCAP
should contain either a terminal description
(with newlines stripped out),
or a file name indicating where the information required by the
.I TERM
environment variable is stored.
.SS "\fITERMINFO\fP"
.I \%ncurses
can be configured to read terminal type description databases in various
locations using different formats.
This variable overrides the default location.
.bP
Descriptions in
.I \%term\%info
format are normally stored in a directory tree using subdirectories
named by the common first letters of the terminal types named therein.
This is the scheme used in System\ V.
.bP
If
.I \%ncurses
is configured to use hashed databases,
then
.I \%TERM\%INFO
may name its location,
such as
.IR \%/usr/share/terminfo.db ,
rather than
.IR \%/usr/share/terminfo/ .
.PP
The hashed database uses less disk space and is a little faster than the
directory tree.
However,
some applications assume the existence of the directory tree,
and read it directly
rather than using the
.I \%term\%info
API.
.bP
If
.I \%ncurses
is configured with
.I termcap
support,
this variable may contain the location of a
.I \%termcap
file.
.bP
If the value of
.I \%TERM\%INFO
begins with \*(``hex:\*('' or \*(``b64:\*('',
.I \%ncurses
uses the remainder of the value as a compiled
.I \%term\%info
description.
You might produce the base64 format using \fB\%infocmp\fP(1M).
.RS 4
.IP
.EX
TERMINFO=$(infocmp \-0 \-Q2 \-q)
export TERMINFO
.EE
.RE
.IP
The compiled description is used only if it corresponds to the terminal
type identified by
.IR TERM .
.PP
Setting
.I \%TERM\%INFO
is the simplest,
but not the only,
way to direct
.I \%ncurses
to a terminal database.
The search path is as follows.
.bP
the last terminal database to which the running
.I \%ncurses
application wrote,
if any
.bP
the location specified by the
.I \%TERM\%INFO
environment variable
.bP
.I $HOME/.terminfo
.bP
locations listed in the
.I \%TERMINFO_DIRS
environment variable
.ds td \" empty
.if !'/usr/share/terminfo'no default value' .as td /usr/share/terminfo
.if !'/usr/share/terminfo\*(td'' \{\
.bP
location(s) configured and compiled into
.I \%ncurses
.RS
.if !'\*(td'' \{\
.bP
.I \%/usr/share/terminfo
.\}
.if !'@TERMINFO'' .if !'\*(td'/usr/share/terminfo' \{\
.bP
.I \%/usr/share/terminfo
.\}
.\}
.RE
.SS "\fITERMINFO_DIRS\fP"
This variable specifies a list of locations,
akin to
.IR PATH ,
in which
.I \%ncurses
searches for the terminal type descriptions described by
.I \%TERMINFO
above.
The list items are separated by colons on Unix
and semicolons on OS/2 EMX.
System\ V
.I \%term\%info
lacks a corresponding feature;
.I \%TERMINFO_DIRS
is an
.I \%ncurses
extension.
.SS "\fITERMPATH\fP"
If
.I \%TERMCAP
does not hold a terminal type description or file name,
then
.I \%ncurses
checks the contents of
.IR \%TERMPATH ,
a list of locations,
akin to
.IR PATH ,
in which it searches for
.I termcap
terminal type descriptions.
The list items are separated by colons on Unix
and semicolons on OS/2 EMX.
.PP
If both
.I \%TERMCAP
and
.I \%TERMPATH
are unset or invalid,
.I \%ncurses
searches for the files
.IR \%/etc/termcap ,
.IR \%/usr/share/misc/termcap ,
and
.IR \%$HOME/.termcap ,
in that order.
.SH "ALTERNATE CONFIGURATIONS"
Many different
.I \%ncurses
configurations are possible,
determined by the options given to the
.I \%configure
script when building the library.
Run the script with the
.B \-\-help
option to peruse them all.
A few are of particular significance to the application developer
employing
.IR \%ncurses .
.TP 5
.B \-\-disable\-overwrite
The standard C preprocessor inclusion for the
.I curses
library is as follows.
.RS 5
.PP
.RS 4
.EX
.\" The dummy character prevents undesired rewriting of the next line on
.\" installation of the man page.
\fB#\&include <curses.h>\fP
.EE
.RE
.PP
This option is used to avoid file name conflicts between
.I \%ncurses
and an existing
.I curses
installation on the system.
If
.I \%ncurses
is installed disabling overwrite,
it puts its header files in a subdirectory.
Here is an example.
.PP
.RS 4
.EX
.\" The dummy character prevents undesired rewriting of the next line on
.\" installation of the man page.
\fB#\&include <ncurses/curses.h>\fP
.EE
.RE
.PP
Installation also omits a symbolic link that would cause the compiler's
.B \-lcurses
option to link object files with
.I \%ncurses
instead of the system
.I curses
library.
.PP
The directory used by this configuration of
.I \%ncurses
is shown in section \*(``SYNOPSIS\*('' above.
.RE
.TP 5
.B \-\-enable\-widec
The configure script renames the library and
(if the \fB\-\-disable\-overwrite\fP option is used)
puts the header files in a different subdirectory.
All of the library names have a \*(``w\*('' appended to them,
i.e., instead of
.RS 5
.PP
.RS 4
.EX
\fB\-lncurses\fP
.EE
.RE
.PP
you link with
.PP
.RS 4
.EX
\fB\-lncursesw\fP
.EE
.RE
.PP
You must also enable the wide-character features in the header file
when compiling for the wide-character library
to use the extended (wide-character) functions.
The symbol which enables these features has changed
since X/Open Curses, Issue 4:
.bP
Originally, the wide-character feature required the symbol
\fB_XOPEN_SOURCE_EXTENDED\fP
but that was only valid for XPG4 (1996).
.bP
Later, that was deemed conflicting with \fB_XOPEN_SOURCE\fP defined to 500.
.bP
As of mid-2018,
none of the features in this implementation require a \fB_XOPEN_SOURCE\fP
feature greater than 600.
However, X/Open Curses, Issue 7 (2009) recommends defining it to 700.
.bP
Alternatively, you can enable the feature by defining \fBNCURSES_WIDECHAR\fP
with the caveat that some other header file than \fBcurses.h\fP
may require a specific value for \fB_XOPEN_SOURCE\fP
(or a system-specific symbol).
.PP
The \fI\%curses.h\fP header file installed for the wide-character
library is designed to be compatible with the non-wide library's header.
Only the size of the \fI\%WINDOW\fP structure differs;
few applications require more than pointers to \fI\%WINDOW\fPs.
.PP
If the headers are installed allowing overwrite,
the wide-character library's headers should be installed last,
to allow applications to be built using either library
from the same set of headers.
.RE
.TP 5
.B \-\-with\-pthread
The configure script renames the library.
All of the library names have a \*(``t\*('' appended to them
(before any \*(``w\*('' added by \fB\-\-enable\-widec\fP).
.IP
The global variables such as \fBLINES\fP are replaced by macros to
allow read-only access.
At the same time, setter-functions are provided to set these values.
Some applications (very few) may require changes to work with this convention.
.TP 5
.B \-\-with\-shared
.tQ
.B \-\-with\-normal
.tQ
.B \-\-with\-debug
.tQ
.B \-\-with\-profile
The shared and normal (static) library names differ by their suffixes,
e.g., \fBlibncurses.so\fP and \fBlibncurses.a\fP.
The debug and profiling libraries add a \*(``_g\*(''
and a \*(``_p\*('' to the root names respectively,
e.g., \fBlibncurses_g.a\fP and \fBlibncurses_p.a\fP.
.TP 5
.B \-\-with\-termlib
Low-level functions which do not depend upon whether the library
supports wide-characters, are provided in the tinfo library.
.IP
By doing this, it is possible to share the tinfo library between
wide/normal configurations as well as reduce the size of the library
when only low-level functions are needed.
.IP
Those functions are described in these pages:
.RS
.bP
\fB\%curs_extend\fP(3X) \- miscellaneous \fIcurses\fP extensions
.bP
\fB\%curs_inopts\fP(3X) \- \fIcurses\fP input options
.bP
\fB\%curs_kernel\fP(3X) \- low-level \fIcurses\fP routines
.bP
\fB\%curs_termattrs\fP(3X) \- \fIcurses\fP environment query routines
.bP
\fB\%curs_termcap\fP(3X) \- \fIcurses\fP emulation of \fItermcap\fP
.bP
\fB\%curs_terminfo\fP(3X) \- \fIcurses\fP interface to \fIterminfo\fP
database
.bP
\fB\%curs_util\fP(3X) \- miscellaneous \fIcurses\fP utility routines
.RE
.TP 5
.B \-\-with\-trace
The \fBtrace\fP function normally resides in the debug library,
but it is sometimes useful to configure this in the shared library.
Configure scripts should check for the function's existence rather
than assuming it is always in the debug library.
.SH FILES
.TP
.I /usr/share/tabset
tab stop initialization database
.TP
.I /usr/share/terminfo
compiled terminal capability database
.SH NOTES
X/Open Curses permits most functions it specifies to be made available
as macros as well.
.\" See X/Open Curses Issue 4, Version 2, pp. 227-234.
.\" See X/Open Curses Issue 7, pp. 311-318.
\fI\%ncurses\fP does so
.bP
for functions that return values via their parameters,
.bP
to support obsolete features,
.bP
to reuse functions
(for example,
those that move the cursor before another operation),
and
.bP
in a few special cases.
.PP
If the standard output file descriptor of an
.I \%ncurses
program is redirected to something that is not a terminal device,
the library writes screen updates to the standard error file descriptor.
This was an undocumented feature of SVr3
.IR curses .
.PP
See subsection \*(``Header Files\*('' below regarding symbols exposed by
inclusion of \fI\%curses.h\fP.
.SH EXTENSIONS
.I \%ncurses
enables an application to capture mouse events on certain terminals,
including \fI\%xterm\fP(1);
see \fB\%curs_mouse\fP(3X).
.PP
.I \%ncurses
provides a means of responding to window resizing events,
as when running in a GUI terminal emulator application such as
.IR \%xterm ;
see \fB\%resizeterm\fP(3X) and \fB\%wresize\fP(3X).
.PP
.I \%ncurses
allows an application to query the terminal for the presence of a wide
variety of special keys;
see \fB\%has_key\fP(3X).
.PP
.I \%ncurses
extends the fixed set of function key capabilities specified by X/Open
Curses by allowing the application programmer to define additional key
events at runtime;
see
\fB\%define_key\fP(3X),
\fB\%key_defined\fP(3X),
\fB\%keybound\fP(3X),
and
\fB\%keyok\fP(3X).
.PP
.I \%ncurses
can exploit the capabilities of terminals implementing ISO\ 6429/ECMA-48
SGR\ 39 and SGR\ 49 sequences,
which allow an application to reset the terminal to its original
foreground and background colors.
From a user's perspective,
the application is able to draw colored text on a background whose color
is set independently,
providing better control over color contrasts.
See \fB\%default_colors\fP(3X).
.PP
An
.I \%ncurses
application can eschew knowledge of
.I \%SCREEN
and
.I \%WINDOW
structure internals,
instead using accessor functions such as
\fB\%is_cbreak\fP(3X) and
\fB\%is_scrollok\fP(3X).
.PP
.I \%ncurses
enables an application to direct its output to a printer attached to the
terminal device;
see \fB\%curs_print\fP(3X).
.PP
.I \%ncurses
offers \fB\%slk_attr\fP(3X) as a counterpart of \fB\%attr_get\fP(3X) for
soft-label key lines,
and \fB\%extended_slk_color\fP(3X) as a form of \fB\%slk_color\fP(3X)
that can gather color information from them when many colors are
supported.
.PP
.I \%ncurses
permits modification of \fB\%unctrl\fP(3X)'s behavior;
see \fB\%use_legacy_coding\fP(3X).
.PP
Rudimentary support for multi-threaded applications may be available;
see \fBcurs_threads\fP(3X).
.PP
Functions that ease the management of multiple screens can be exposed;
see \fBcurs_sp_funcs\fP(3X).
.PP
To aid applications to debug their memory usage,
.I \%ncurses
optionally offers functions to more aggressively free memory it
dynamically allocates itself;
see \fBcurs_memleaks\fP(3X).
.PP
The library facilitates auditing and troubleshooting of its behavior;
see \fBcurs_trace\fP(3X).
.PP
Compiling
.I \%ncurses
with the option
.B \%\-DUSE_GETCAP
causes it to fall back to reading
.I \%/etc/termcap
if the terminal setup code cannot find a
.I \%term\%info
entry corresponding to
.IR TERM .
Use of this feature is not recommended,
as it essentially includes an entire
.I termcap
compiler in the
.I \%ncurses
startup code,
at a cost in memory usage and application launch latency.
.PP
.I \%PDCurses
and NetBSD
.I curses
incorporate some
.I \%ncurses
extensions.
Individual man pages indicate where this is the case.
.SH PORTABILITY
X/Open Curses defines two levels of conformance,
\*(``base\*('' and \*(``enhanced\*(''.
The latter includes several additional features,
such as wide-character and color support.
.I \%ncurses
intends base-level conformance with X/Open Curses,
and supports all features of its enhanced level
except the
.I \%untic
utility.
.PP
Differences between X/Open Curses and
.I \%ncurses
are documented in the \*(``PORTABILITY\*('' sections of applicable man
pages.
.SS "Error Checking"
In many cases, X/Open Curses is vague about error conditions,
omitting some of the SVr4 documentation.
.PP
Unlike other implementations,
.I \%ncurses
checks pointer parameters,
such as those to
.I \%WINDOW
structures,
to ensure that they are not null.
This is done primarily to guard against programmer error.
The standard interface does not provide a way for the library
to tell an application which of several possible errors occurred.
An application that relies on
.I \%ncurses
to check its function parameters for validity limits its portability and
robustness.
.SS "Padding Differences"
In historical
.I curses
implementations,
delays embedded in the
.I \%term\%info
capabilities
.B \%carriage_return
.RB ( cr ),
.B \%scroll_forward
.RB ( ind ),
.B \%cursor_left
.RB ( cub1 ),
.B \%form_feed
.RB ( ff ),
and
.B \%tab
.RB ( ht )
activated corresponding delay bits in the Unix terminal driver.
.I \%ncurses
performs all padding by sending NUL bytes to the device.
This method is slightly more expensive,
but narrows the interface to the Unix kernel significantly and
correspondingly increases the package's portability.
.SS "Header Files"
The header file
.I \%curses.h
itself includes the header files
.I \%stdio.h
and
.IR \%unctrl.h .
.PP
X/Open Curses has more to say,
.RS 4
.PP
The inclusion of
.I \%curses.h
may make visible all symbols from the headers
.IR \%stdio.h ,
.IR \%term.h ,
.IR \%termios.h ,
and
.IR \%wchar.h .
.RE
.PP
but does not finish the story.
A more complete account follows.
.bP
The first
.IR curses ","
in 4BSD,
provided a
.I \%curses.h
file.
.IP
BSD
.I curses
code included
.I \%curses.h
and
.I \%unctrl.h
from an internal header file
.IR \%curses.ext ,
where
\*(``ext\*('' abbreviated \*(``externs\*(''.
.IP
The implementations of
.I \%printw
and
.I \%scanw
used undocumented internal functions of the standard I/O library
.RI ( _doprnt
and
.IR _doscan ),
but nothing in
.I \%curses.h
itself relied upon
.IR \%stdio.h .
.bP
SVr2
.I curses
added
.IR \%newterm ,
which relies upon
.I \%stdio.h
because its function prototype employs the
.I FILE
type.
.IP
SVr4
.I curses
added
.I \%putwin
and
.IR \%getwin ,
which also use
.IR \%stdio.h .
.IP
X/Open Curses specifies all three of these functions.
.IP
SVr4
.I curses
and X/Open Curses do not require the developer to include
.I \%stdio.h
before
.IR \%curses.h .
Both document use of
.I curses
as requiring only
.IR \%curses.h .
.IP
As a result,
standard
.I \%curses.h
always includes
.IR \%stdio.h .
.bP
X/Open Curses and SVr4
.I curses
are inconsistent with respect to
.IR \%unctrl.h .
.IP
As noted in \fBcurs_util\fP(3X),
.I \%ncurses
includes
.I \%unctrl.h
from
.I \%curses.h
(as SVr4 does).
.bP
X/Open Curses's comments about
.I \%term.h
and
.I \%termios.h
may refer to HP-UX and AIX.
.IP
HP-UX
.I curses
includes
.I \%term.h
from
.I \%curses.h
to declare
.I \%setupterm
in
.IR \%curses.h ,
but
.I \%ncurses
and Solaris
.I curses
do not.
.IP
AIX
.I curses
includes
.I \%term.h
and
.IR \%termios.h .
Again,
.I \%ncurses
and Solaris
.I curses
do not.
.bP
X/Open Curses says that
.I \%curses.h
.B may
include
.IR \%term.h ,
but does not require it to do so.
.IP
Some programs use functions declared in both
.I \%curses.h
and
.IR \%term.h ,
and must include both header files in the same module.
Very old versions of AIX
.I curses
required inclusion of
.I \%curses.h
before
.IR \%term.h .
.IP
The header files supplied by
.I \%ncurses
include the standard library headers required for its declarations,
so
.IR \%ncurses 's
own header files can be included in any order.
But for portability,
you should include
.I \%curses.h
before
.IR \%term.h .
.bP
X/Open Curses says \*(``may make visible\*('' because including a header
file does not necessarily make visible all of the symbols in it
(consider
.B \%#ifdef
and similar).
.IP
For instance,
.IR \%ncurses 's
.I \%curses.h
.B may \" bold to contrast with preceding italic
include
.I \%wchar.h
if the proper symbol is defined,
and if
.I \%ncurses
is configured for wide-character support.
If
.I \%wchar.h
is included,
its symbols
.B may \" bold for consistency in this paragraph
be made visible depending on the value of the
.B _XOPEN_SOURCE
feature test macro.
.bP
X/Open Curses mandates an application's inclusion of one standard C
library header in a special case:
.I \%stdarg.h
before
.I \%curses.h
to prototype the functions
.I \%vw_printw
and
.I \%vw_scanw
(as well as the obsolete
.I \%vwprintw
and
.IR \%vwscanw ).
Each of these takes a variadic argument list,
a
.I \%va_list
parameter,
like that of \fI\%printf\fP(3).
.IP
SVr3
.I curses
introduced
the two obsolete functions,
and X/Open Curses the others.
In between,
SVr4
.I curses
provided for the possibility that an application might include either
.I \%varargs.h
or
.IR \%stdarg.h .
These represented contrasting approaches to handling variadic
argument lists.
The older interface,
.IR \%varargs.h ,
used a pointer to
.I char \" V7, 32V, System III, 3BSD
for variadic functions'
.I \%va_list
parameter.
Later,
the list acquired its own standard data type,
.IR \%va_list ,
defined in
.IR \%stdarg.h ,
empowering the compiler to check the types of a function call's actual
parameters against the formal ones declared in its prototype.
.IP
No conforming implementations of X/Open Curses require an application
to include
.I \%stdarg.h
before
.I \%curses.h
because they either have allowed for a special type,
or,
like
.IR \%ncurses ,
they include
.I \%stdarg.h
themselves to provide a portable interface.
.SH AUTHORS
Zeyd M. Ben-Halim,
Eric S. Raymond,
Thomas E. Dickey.
Based on
.I \%pcurses
by Pavel Curtis.
.SH SEE ALSO
\fB\%curs_variables\fP(3X),
\fB\%terminfo\fP(5),
\fB\%user_caps\fP(5)
